Immunomodulation by anti-cd3 immunotoxins to treat cancers not uniformly bearing surface cd3

ABSTRACT

Methods of modulating the immune systems of patients suffering from cancers that do not hear, or do not uniformly bear, surface CD3 are provided. The methods involve administering an anti-CD3 immunotoxin (e.g. A-dmDT390-bisFv(UCHT1)), to the patient so a to cause the patient&#39;s Immune system to recognize and destroy non-CD3 cancer cells.

BACKGROUND OP THE INVENTION

1. Field of the Invention

The invention generally relates to methods of treating patients suffering from cancers that do not bear, or do not uniformly bear, surface CD3 epitopes. In particular, the methods involve administering anti-CD3 immunotoxins to modulate the immune systems of such patient and achieve long-term immune protection against non-CD3 cancers.

2. Background of the Invention

Two important tools in the treatment of cancer are immunotoxins and immunomodulatory agents. Immunotoxins are anti-human recombinant fusion proteins that target and kill specific types of cancer mils. Targeting is typically mediated via a targeting portion of the protein (e.g. a modified antibody or antibody fragment specific for binding to a particular epitope of interest), and killing is typically carried out by a toxin moiety that is attached to the targeting portion. Upon administration, immunotoxins thus directly target and bind to cancer cells that display the epitope of interest, and the toxic portion of the molecule then kills the cell to which it is bound. Destruction of cancer cells by immunotoxins thus occurs within the relatively short time frame during which they are in circulation, e.g. within hours or days of administration.

In contrast, immunomodulatory agents have a completely different mode of action, Rather than killing cancer cells outright, they work by “resetting” the immune system so that it recognizes and destroys cancer cells on its own. In cases of full-blown cancer, an individual's immune system has not been able to destroy cancer cells, possibly because they arise from pre-existing cells of the body and are thus recognized as innocuous “self” cells rather than as potentially dangerous “foreign” invaders. Immunomodulatory agents work by altering existing immune cells, thereby providing an opportunity for immune cell replication and the development of new lineages of immune cells that do recognize the cancer cells as “foreign”. In other words, the body's immune tolerance of the cancer antigens is broken by the immunomodulatory agent. As a result of this mode of action, treatment with immunomodulatory agents displays tumor regression kinetics that differ from those of immunotoxins. The effects are usually delayed and can take a few months or even years to achieve their maximum levels. During this time the immune system reconstitutes itself and, if conditions are right, is “retrained” to recognize cancer cells as foreign and mount an immune response against the cancer if it recurs. After treatment with an immunomodulatory agent, the course of tumor regression may not be linear but rather punctuated by the development of new tumors followed by regression as the body's immune system recognizes and then mounts a response to the tumor.

Ideally, for some cancer treatment protocols, a “short-acting” anti-cancer agent is used in conjunction with a “long-acting” immunomodulatory agent, the farmer resulting in an immediate killing of cancer cells, and the latter eliciting long-term anti-cancer protection. Some agents of both types are known and have been used with success. However, given the many types of cancers, the complexity of the disease, and the limited and variable efficacies of existing agents, this strategy is not always successful, and there remains an ongoing need to identify new anti-cancer agents and/or a need for new ways of using existing agents. In addition, currently known immunomodulatory agents typically have adverse side effects such as the development of autoimmune diseases. This likely results from the breaking of tolerance to self antigens during repopulation, which, in addition to the cancer cells, the immune system then “sees” as abnormal.

It would be a boon to have available additional immunomodulatory agents which can be used to stimulate the body's own cancer fighting abilities as described above, in particular with respect to preventing or treating recurrences or metastasis of the cancer over time. Further, the discovery of immunomodulatory agents that do not cause autoimmune disease in patients would be highly desirable.

U.S. Pat. Nos. 7,696,338 and 8,217,158 (Neville, Jr., et al.), the complete contents of which are herein incorporated by reference, describe methods of treating autoimmune diseases and CD3 bearing T cell leukemia or lymphoma using an antibody-DT mutant immunotoxin which routes by the anti-CD3 pathway. However, these patents do not describe the use of these immunotoxins as immunodulatory agents.

SUMMARY OF THE INVENTION

The invention provides a new use for the anti-CD3 immunotoxins described in U.S. Pat. Nos. 7,696,338 and 8,217,158. The immunotoxins comprise antigen-binding domains of an anti-CD3 antibody and a portion of the diphtheria toxin protein. An exemplary immunotoxin of this type has been successfully used in clinical trials to treat CD3 bearing (i.e. T-cell) lymphomas and leukemias. In these cases, the rationale for administering the immunotoxin was to target and destroy extant carver cells which bear CD3 epitopes, thereby providing a short-term, front line defense against the disease.

However, it has now been surprisingly discovered that the immunotoxin may effectively be used as an immunomodulating agent and can thus be used to provide long-term, far-reaching anti-cancer effects that are not related to (are separate or apart from) their immunotoxin activity. Without being bound by theory, it is believed that when administered, these agents attack and kill normal immune cells which bear CD3 epitopes (e.g. T cells), thereby depleting the immune cell population. The depletion is transient or temporary, and is followed by repopulation with new, peripheral T cells (homeostatic repopulation) which are susceptible to retraining. When exposed to cancer cell antigens, the new cadre of immune cells learns to recognize the antigens, and hence the cancer cells, as abnormal, to distinguish them from innocuous “self” or otherwise healthy tissue. In other words, use of these agents results in resetting or retraining of the immune system of the patient, and provides the patient with the ability to “naturally” fight the disease using his/her own immune defense system when cancer cells are later encountered. The discovery of this heretofore unrealized property of these immunotoxin molecules has resulted in the development of methods of treating cancers other than those of T-cell origin, i.e. methods for destroying or killing cancer cells which do not bear, or do not uniformly bear, CD3 epitopes. In particular, the agents are used to modulate a patient's immune system to recognize cancer cells as abnormal and to destroy them if/when they arise metastatically or during and after recurrence of the disease. Significantly, and in contrast to other immunomodulatory agents, the immunotoxins of the invention break immune tolerance of the tumor without breaking immune tolerance to self antigens and causing autoimmune diseases.

It is an object of this invention to provide methods of providing immunomodulation to a patient suffering from a cancer which does not bear, or does not uniformly bear, surface CD3 epitopes. The method comprises 1) administering to the patient an anti-CD3 specific immunotoxin in an amount sufficient to deplete extant T-cells of said patient and 2) allowing repopulation and maturation of new T cells in said patient in the presence of said non-CD3 cancer cell antigens. In some aspects, the non-CD3 cancer cell antigens are released into circulation as a result of administering an antigen releasing anti-cancer therapy, for example, radiation therapy. In other aspects, the step of administering does not break immune tolerance to self antigens in said patient. The methods may further comprise a step of providing the non-CD3 cancer cell antigens to a patient to boost an immune response of the patient to the non-CD3 cancer cell antigens, at a period of time after the step of allowing. The step of providing may be performed after a recurrence of the cancer. In some aspects of the invention, the anti-CD3 specific immunotoxin is A-dmDT390-bisFv (UCHT1).

The invention also provides methods of lengthening survival time of a patient suffering hum a cancer which does not bear, or does not uniformly bear, surface CD3 epitopes. The methods comprise 1) administering to the patient an anti-CD3 specific immunotoxin in an amount sufficient to deplete extant T-cells of the patient, and allowing repopulation and maturation of new T cells in the patient in the presence of the non-CD3 cancer cell antigens.

The invention also provides methods of preparing the immune system of a patient to recognize and kill metastatic and/or recurrent cancer, wherein the patient is suffering flow a cancer which does not bear, or does not uniformly bear, surface CD3 epitopes. The methods comprise 1) administering to the patient an anti-CD3 specific immunotoxin in an amount sufficient to deplete extant T-cells of the patient; and allowing repopulation and maturation of new T cells in the patient in the presence of the non-CD3 cancer cell antigens.

Other features and advantages of the present invention will be set forth in the description of invention that follows, and in part will be apparent from the description or may be learned by practice of the invention. The invention will be realized and attained by the compositions and methods particularly pointed out in the written description and claims hereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. % of the initial Modified Severity Weighted Assessment Tool (mSWAT) score versus time after a 4-day treatment period. The mSWAT score represents the skin tumor burden and is measured by determining the % surface area of skin involved times a multiplier that is 1 for patch, 2 for plaque and 4 for tumor.

FIG. 2. Amino acid sequence of A-dmDT390-bisFv(UCHT1) (SEQ ID NO: 1).

FIG. 3A and B. Amino acid sequences of exemplary fusion proteins that may be used in the practice of the invention (SEQ ID NOS: 2 and 3).

DETAILED DESCRIPTION

The present invention provides a new use for the immunotoxin molecules described in U.S. Pat. Nos. 7,696,338 and 8,217,158 to Neville, the complete contents of both of which are hereby incorporated by reference in entirely. The new uses include administration of the molecules'to bring about immunomodulation in patients with cancers that do not bear, or do not uniformly bear, CD3 antigens. Prior to the present invention, these agents were not administered to such patients because these agents were designed as anti-CD3 toxins and the subject cancers do not bear, or do not uniformly bear, CD3 antigens.

U.S. Pat. Nos. 7,696,338 and 8,217,158 describe various embodiments of these immunotoxins in detail. The immunotoxins are chimeras or fusion proteins which comprise a recombinant toxin moiety linked to an antibody moiety that is specific for binding to CD3 epitopes. The antibody moiety is responsible for binding the immunotoxin to the CD3εγ subunit of the T cell receptor complex, enabling the molecule to specifically target and bind to T-cells bearing the CD3 receptor. Once bound, the toxin moiety of the molecule enters and kills the cells. In some embodiments, the toxin moiety is, for example, a truncated diphtheria toxin (DT) moiety or pseudomonas exotoxin A (ETA) toxin moiety, and the antibody moiety comprises two single chain Fvs of and anti-CD3 antibody. The amino acid sequence of several exemplary immunotoxins that may be used in the practice of the invention are shown in FIGS. 2-3 and SEQ ID NOS: 1-3. In particular, the amino acid sequence of A-dmDT390-bisFv(UCHT1) is shown in FIG. 2 and set forth in SEQ ID NO: 1. Variants of these sequences may also be employed, e.g. variants with conservatively substituted amino acid sequences, proteolytic fragments, variants that do and do not include an amino terminal Met residue, codon optimized and/or humanized variants, etc. In addition, serine protease cleavage at e.g. furin cleavage site RVRR:SVGS (see residues 191-198 of SEQ ID NO: 1) or at other sites may occur, without disrupting the disulfide bridge between cysteines 188 and 202 Any such variant may be utilized to treat or prevent cancer as described herein, so long as immunotoxin activity is retained in the variant. Suitable nucleic acid molecules for encoding the immunotoxins include any that produce the indicated proteins when transcribed/translated (e.g. RNA, DNA, etc.) including genes and/or recombinant genes whether isolated, present in a vector, or present in a cell.

The methods take advantage of the sophisticated defense mechanisms of jawed vertebrates, including humans, i.e. the ability to adapt over time to recognize specific pathogens more efficiently. This adaptive (or acquired) immunity creates immunological memory after an initial response to antigens of a specific pathogen (or in this case, cancer cell antigens) leading to an enhanced response to subsequent encounters with the same antigens. (This process of acquired immunity is the also basis of vaccination.) The methods involve identifying a patient in need of immunomodulation and administering an immunotoxin as described herein. for the purpose of transiently or temporarily depleting the patient's T cells. The method is carried out under conditions in which, when natural repopulation of the T cells ensues, the new T cells are exposed to circulating cancer cell antigens. Exposure to cancer cell antigens during repopulation results in a sensitization of the new T cell population to the antigens, and the development of immunological memory so that, upon subsequent encounters with the same cancer antigens, they are recognized by the immune system and attar-ked and killed. Therefore, metastatic and/or recurrent tumors that develop later are eventually resolved (destroyed) by the body's own immune system, with or without further anti-cancer treatment. In some embodiment, described in detail below, the methods further include a step or steps of priming the immune system by additional exposures of the immune system to the cancer antigens, e.g. by releasing antigens into the circulatory system via radiation of metastastic or recurring tumors. The use of the methods thus facilitates the treatment of metastatic and/or recurring cancer ahead of time (i.e. prior to the metastasis or recurrence) by augmenting the patient's natural ability to conduct immune surveillance on an ongoing basis and fight the development of tumors. Practice of the methods lengthens the survival time of cancer patients, and prevents and/or aids in the eradication of metastatic or recurring tumors and cancerous lesions.

In one aspect of the invention, subjects who are identified as suitable for treatment using the methods of the invention are those who are diagnosed as suffering from a cancer in which the cancer cells do not bear surface CD3 epitopes i.e. CD3 epitopes are not present on (are absent from) the surface of The cancer cells. Determination of the phenotype of cancer cells with respect to the presence or absence of a particular epitope (e.g. CD3) is well known in the art. For example, samples of tumor cells are obtained and the nature (type, identity. etc.) of the antigens that are displayed is determined or confirmed using immunochemistry, e.g. by exposing the sample to antibodies specific for one or more antigens of interest (e.g. CD3) and measuring the extent of binding, if any, of the antibodies to the cancer cells using standard technologies, e.g. ELISA reactions, flow cytometry, etc. Cancer which do not bear surface CD3 epitopes include any non-T cell leukemia or lymphoma (i.e. arty cancer that is not a T cell leukemia or lymphoma) such as, but are not limited to: some cases of acute lymphoblastic leukemia (ALL) e.g. those in which the cancer celli do not uniformly bear CD3 epitopes; acute myeloid leukemia (AML); adrenocortical carcinoma; atypical teratoid/rhabdoid tumors; central nervous system cancers; basal cell carcinoma (e.g. nonmelanoma); bile duct cancer; extrahepatic bladder cancer; bone cancers (e.g. Ewing sarcoma family of tumors, osteosarcoma and malignant fibrous histiocytoma; brain stem glioma; brain tumors (e.g. astrocytomas, brain and spinal cord tumors, CNS atypical teratoid/rhabdoid tumor, CNS embryonal tumors, CNS germ cell tumors, etc.); craniopharyngioma, ependymom; breast cancer, bronchial tumors, Burkitt lymphoma gastrointestinal tumors; cardiac (heart) tumors; cervical cancer chordoma; chronic lymphocytic leukemia (CLL); chronic myelogenous leukemia (CML); chronic myeloproliferative disorder; colon cancer, colorectal cancer, crainopharyngioma, cutaneous T-Cell lymphoma; extrahepatic bile duct tumors; ductal carcinoma in situ (DCIS); embryonal tumors; endometrial cancer; esophageal cancer esthesioneuroblastoma; Ewing sarcoma; extracranial germ cell tumor; extragonadal germ cell tumor, eye cancers (intraocular melanoma, retinoblastoma); fibrous histiocytoma of bone; osteosarcoma; gallbladder cancer, gastric (stomach) cancer; gastrointestinal carcinoid tumor; gastrointestinal stomal tumors (GIST); gestational trophoblastic tumor, glioma; hairy cell leukemia; head and neck cancer; heart cancer; hepatocellular (liver) cancer, hypopharyngeal cancer; intraocular melanoma; islet cell tumors; pancreatic neuroendocrine tumors; kidney (e.g. renal cell and Wilms tumor); langerhans cell histiocytosis; laryngeal cancer, leukemia; liver cancer (primary); lobular carcinoma in situ (LCIS); lung cancer (non-small cell, small cell); lymphomas; Waldenström macroglobulinemia; male breast cancer; malignant mesothelioma, metastatic squamous neck cancer with occult primary midline tract carcinoma involving NUT gene; mouth cancer, multiple endocrine neoplasia syndromes; myelodysplastic syndromes; myelodysplastic/myeloproliferative neoplasms; Chronic Myelogenous Leukemia (CML); Acute Myeloid Leukemia (AML); multiple myeloma; chronic myeloproliferative disorders; nasal cavity and paranasal sinus cancer, nasopharyngeal cancer; neuroblastoma; non-Hodgkin lymphoma; oral cancer; oral cavity cancer, lip and oropharyngeal cancer, osteosarcoma and malignant fibrous histiocytoma of bone; ovarian cancer, pancreatic cancer, pancreatic neuroendocrine tumors (Islet Cell tumors); papillomatosis; paraganglioma; parathyroid cancer; penile cancer; pharyngeal cancer, neochromocroma; pituitary tumor, plasma cell neoplasm/multiple myeloma; pleuropulmonary blastoma; CNS lymphoma; prostate cancer, rectal cancer; renal cell (kidney) cancer; salivary gland cancer, sarcomas (Ewing, Kaposi, osteosarcoma, rhabdomyosarcoma, soft tissue, uterine); skin cancers (melanoma, Merkel cell carcinoma, nonmelanoma); small cell lung cancer, small intestine cancer; squamous cell carcinoma; squamous neck cancer with occult primary, metastatic stomach (gastric) cancer; testicular cancer, throat cancer; thymoma and thymic carcinoma; thyroid canter, transitional cell cancer of the renal pelvis and ureter, trophoblastic tumor, gestational; urethral cancer; uterine cancer, endometrial cancer, uterine sarcoma; vaginal cancer; vulvar dancer, Waldenström macroglobulinemia; Wilma tumor; nasal cavity and paranasal sinus cancer; nasopharyngeal cancer, neuroblastoma; non-small cell lung cancer, and metastases and recurrences thereof.

In other aspects of the invention, the patients suffering from cancers that do not uniformly bear surface CD3 epitopes, i.e. CD3 epitopes may be present on some but not all of the cancer cells of the tumor, may be treated with the immunotoxin A-dmDT390-bisFv(UCCHT1). For example, in T-ALL, many patients have tumor blast cells do not display surface CD3 but there are also many patients whose blasts display between 10% and 80% CD3. The present method is beneficial for the treatment of such cancers because, even though administering a CD3 toxic agent would kill the portion of the cells that do display CD3, cancer cells that do not display CD3 would not be destroyed. In this aspect, administration of the immunotoxins described herein will kill those cancer cells that do display CD3 during the short time frame when the immunotoxins are in circulation. However, the non-CD3 portion of the cells are not killed outright by the immunotoxin (although they may be destroyed by administration of another agent), but will be subject to attack by the patient's immune system after depletion/repopulation as described herein.

The present invention involves administering the immunotoxic agents described herein to patients in a therapeutically beneficial quantity, e.g. a quantity that results is depletion of the T cell population of the patient to a level that is sufficient to elicit repopulation of the immune system. Depletion of the T cell population refers to the destruction or killing of at least about 90 to 99% or more (e.g. 100%) of the T cells present in the subject, but in some cases killing of about 50% or more (e.g. 55, 60, 65, 70, 75 80 or 85%) may suffice.

The methods of the invention are carried out by administering compositions which include the fusion proteins described herein, or nucleic acid sequences encoding them, and a pharmacologically suitable (physiologically compatible) carrier. The compositions are also encompassed by the invention. The preparation of such compositions is well known to those of skill in the art. Typically, such compositions are prepared either as liquid solutions or suspensions. The active ingredients may be mixed with excipients which are pharmaceutically acceptable and compatible with the active ingredients. Suitable excipients are, for example, water, saline, dextrose, glycerol, ethanol and the like, or combinations thereof. In addition, the composition may contain minor amounts of auxiliary substances such as wetting or emulsifying agents, pH buffering agents, and the like.

Subjects treated by the methods of the invention are generally mammals, and frequently humans. However, the invention also encompasses veterinary applications e.g. the treatment of animals, especially companion pets, prize livestock, etc.

Those of skill in the art are familiar with the administration of chemotherapeutic agents, and the compositions (preparations) may be administered by any of the many suitable means which are well known, including but not limited to: by injection, inhalation, orally, intravaginally, intranasally, topically, as eye drops, via sprays, etc. Generally, the mode of administration is intravenous or topical In addition, the compositions may be administered in conjunction with other treatment modalities such as substances that boost the immune system, various other chemotherapeutic agents, pain medication, anti-nausea Medication, anti-allergy agents (e.g. anti-histamines), and the like.

The immunotoxins described herein may be administered as immunomodulating agents at any desired time after diagnosis of a cancer, and by any suitable protocol or schedule. They may be administered before, after or at the same time as other anticancer agents. For example, they may be administered prior to the commencement of treatment with other cytotoxic agents or therapies, and/or together with them, or after other cytotoxic agents have been administered, e.g. several days or weeks afterwards. If administered “together” with another anti-cancer agent, they may be provided in separate compositions that are administered within a short time of each other, e.g. within minutes, hours or days, or Ming a single composition that contains at least one (i.e. one or more) immunotoxin and one or more than one other anti-cancer agent, etc.

The amount of agent that is administered may vary according to parameters that are understood by those of skill in the art, e.g. by a skilled medical practitioner. Recommended doses and particular protocols for administration may be established during clinical trials. The amount may vary based on e.g. the body weight, gender, age, overall condition, etc. of the patient, and/or on the type and stage of disease, and whether or not other therapeutic agents are being administered, etc. Generally, the total amount administered during a round of chemotherapy (scheduled to take place over e.g. a period of 5 days) will range from about 10 to about 60 μg/kg of body weight e.g. the amount that is administered may be, for example, about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55 or 60 μg/kg of body weight. Typically, about 20 μg/kg of body weight is administered. This amount is usually administered at multiple times or sessions during a single day of e.g. 1-2 μg/kg of body weight per session, with e.g. 1-6 sessions per day, and usually about 2 sessions per day. The number of weeks for which the treatment proceeds may also vary, depending on the factors which impact dosage fisted above. Generally, 1 week of treatment is carried out, although the number of weeks can be 1, 2, 3, 4, 5, 6, or more, as deemed beneficial for the patient. When practiced in conjunction with radiation therapy, a course of treatment typically last for about 1 week. A course of treatment may be repeated as needed throughout the patient's lifetime, especially if there is a recurrence of the cancer. However, for such repetitions of treatment, in general it is rot necessary to repeat the anti-CD3 immunomodulator, only the local tumor radiation.

Since the fusion proteins of he invention are used as immunomodulators rather than as immunotoxins, other toxic agents and/or other therapies may be used to kill the cancer cells outright, to cause tumor shrinkage, etc. In fact, the CD3 specific immunotoxins described herein would not be effective if used for such short-term, front line therapy since they are specific only for CD3 bearing tumors. Thus, one or more other anti-cancer agents or and-cancer modalities or therapies are also generally administered, examples of which include but are not limited to: cytotoxic immunotoxins targeting the specific tumor or blood vessels growing into the tumor, cytotoxic antineoplastic drugs such as alkylating agents cisplatin, carboplatin, oroxaliplatin; anti-metabolites which masquerade as purines (e.g. azathioprine, mercaptopurine) or pyrimidines; plant alkaloids and terpenoids, e.g. vinca alkaloids such as vincristine, vinblastine, vinorelbine, vindesine; podophyllotoxin, etoposide and teniposide; taxanes such as paclitaxel; type I topoisomerase inhibitors including the camptothecins trinotecan and topotecan, and type II topoisomerase inhibitors such as amsacrine, etoposide, etoposide phosphate, and teniposide; and cytotoxic antibiotics such as actinomycin, anthracyclines, doxonibicin, daunorubicin, valrubicin idarubicin, epirubicin, bleomycin, plicamycin and mitomycin; gene therapy (e.g. to deliver a nucleic acid encoding an anti-cancer agent to a tumor), surgery/resection of tumors; hormonal therapy; administration of angiogenesis inhibitors; administration of other immunomodulating agents or therapies (e.g. allogeneic or autologous hematopoietic stem cell transplantation; by radiation therapy via external beam radiotherapy (EBRT) or internally via brachytherapy, electrochemotherapy; untraviolet (UV) light therapy; etc. In some aspects, initial killing of cancer cells and the resulting release of cancer antigens into the circulation is carried out by local radiation of one or more cancerous lesions, which may be metastatic lesions, e.g. using Stereotactic Body Radiation Therapy (SBRT) techniques, In this case, the amount of radiation that is delivered is typically in the range of from about the typical dose for a solid epithelial tumor ranges from 60 to 80 Gy in total, while lymphomas are treated with 20 to 40 Gy. Preventative (adjuvant) doses are typically around 45-60 Gy (for breast, head, and neck cancers.) Generally, a patient receives about 1.8-2 Gy fractions per exposure. Many factors are considered when selecting a dose, including whether the patient is receiving chemotherapy, patient co-morbidities, whether radiation therapy is being administered before or after surgery, and the degree of success of surgery, etc. There is some evidence that higher doses of radiation (e.g. in the range of 10.20 Gy per exposure) may increase the response rate of lesions outside of the radiation field and thus provide a more marked effect with respect to immunomodulation.

Cancer treatment, including immunomodulation, is generally begun as soon after diagnosis as possible. This is especially advantageous for immunomodulation because the benefits of the treatment are typically not observed for at least weeks, usually months, or even years after the treatment, and it is desirable for the benefits to accrue as soon as possible. Administration is generally coordinated with other therapies that release cancer antigens to provide an opportunity for repopulating T cells to be “trained”. Therefore, the present methods may also include a step of killing tumor cells in a mariner that releases tumor antigens, to facilitate the development of immune cell memory with respect to cancer antigens.

The step of killing cancer cells to release antigen is generally carried out early in treatment, and may be sufficient to put the immune system in condition to monitor, recognize and eradicate new tumors shortly after recurrence without further treatment. However, in other aspects, antigen-releasing therapy may be reapplied later during the course of treatment in order to further boost the immune response, analogous to a vaccination protocol. This may be readily accomplished if the cancer recurs since a treatment that releases antigen can be administered at that time. However, if no visible or detectable recurrence is present, it may be possible to effect boosting by administering tumor cells or antigen-bearing fragments thereof from the original tumors that have been preserved for the purpose. In this case, the cells or fragments can be administered e.g. 3-6 months after the initial treatment as a “booster”, and/or at longer intervals (e.g. yearly) thereafter, if desired.

The examples presented below are intended to illustrate various exemplary aspects of the invention but should not be interpreted so as to limit the invention in any way.

EXAMPLES Example 1. Treatment of Cutaneous T Cell Lymphoma with A-dmDT390-bisFv(UCHT1)

A number of immunomodulators have been used to treat solid cancers such as renal cell cancer and melanoma. Among these are infusions of IL-2 and antibodies directed at the activating lymphocyte epitopes CTLA-4 and the inhibitory lymphocyte epitope PD1 as well as its ligand PD1-L The response rates for anti-CTLA-4, ipilimumab; have been low, around 10-15%. Immunomodulators such as anti-CTLA-4 or IL-2 May have a higher response rate on solid tumors when combined with local radiation therapy of metastatic lesions, likely by increasing the pool of presentable tumor antigen (abscopal effect).

An unfortunate side effect of the immunomodulators IL-2, anti-CTLA-4, anti-PD1 and anti-PD1-L is an increased incidence of autoimmune diseases, presumably because of enhanced T cell activity that breaks tolerance toward self antigens.

A-dmDT390-bisFv (UCHT1), an anti-T cell immunotoxin, is being studied as a treatment for cutaneous T cell lymphoma and other CD3+ malignant diseases. Eighteen patients with CD3+ lymphoma were treated to date in the phase I dose escalation portion of the trial. Fifteen patients received the full course of 8 infusions over 4 days, 4-6 hours apart. The total dose ranged between 20 and 90 mg/kg and 60 μg/kg was determined to be the maximum tolerable dose. 6 patients were treated in a 20 μg/kg dose cohort. Three showed partial responses of skin lesions with the first month. Two of these went on to complete responses at 11 months post treatment. Most of the treated patients (15) allowed a 2 log or greater transient depletion of circulating T cells with a repopulation of these cells, except for the naive CD4 subset, at 20 days.

The results for the resounding patients are presented in FIG. 1. As can be see, the kinetics of decrease in mSWAT exhibits a rapid phase of about 2 months and a slower phase between 3-24 months. As can also be seen, four out of six partial responses of patients converted to complete responses at times ranging between 6 and 24 months following the completion of the 4-day treatment protocol, and no other treatment took place except for patient #2 who received narrow band UV-B after a complete remission and a subsequent relapse. These data are consistent with A-dmDT390-bisFv (UCHT1) acting as an immunomodulator. For these particular patients, it is likely that the anti-T cell immunotoxin has two distinct effects in treating T cell lymphoma: i) it kills malignant T cells thus releasing tumor antigens; and h) it also functions as an immunomodulator Via the depletion of normal T cells and subsequent repopulation that breaks tumor antigen tolerance daring homeostatic T cell proliferation or modification of Tregs. Significantly, in contrast to patients treated with other immunomodulators, patients receiving A-dmDT390-bisFv (UCHT1) did not develop autoimmune diseases.

Example 2. Phase VII Study of A-dmDT390-bisFv (UCHT1) Fusion Protein in Patients with Surface CD3+ Malignant T Cell Disease: Summary of Patients # 2 & 7

Patient #2 is an 82-year-old Caucasian male who developed cutaneous T cell lymphoma (CTCL) with a maculopapular rash on his buttocks and a groin mass. Biopsy of both lesions showed lymphoblastoid T-cell lymphoma. A computed tomography (CT) scan showed diffuse adenopathy. He received six cycles of CHOP chemotherapy (i.e., cyclophosphamide, doxorubcin, vincristine, and methylprednisolone), but after several years the rash recurred. Biopsy again showed CTCL. He did not have node or marrow involvement based on CT scans and bone marrow biopsies and was staged as IB. He was treated with A-dmDT390-bisFv(UCHT1) and achieved a response lasting 17 months, which included partial remission (PR) of 11 months duration and complete remission (CR) of 6 months duration. Patient #2 was then removed from the study due to return of buttock lesions that responded to narrow band UVB, 2.5 years later, he was reenrolled in the study to follow his progress. He has been in complete remission since the UVB treatment. The total duration since treatment with A-dmDT390-bisFv(UCHT1) is 4.4 yrs.

Comment: Administration of the anti-CD3 immunotoxin A-dmDT390-bisFv(UCHT1) was expected to kill a large fraction of tumor cells but was not expected to provide lasting therapeutic value. However, the course of the disease for patient #2 surprisingly showed partial remission, complete remission, relapse and then complete remission for the 4.4. years after administration during which he was followed. Surprisingly, the duration of the effect of administration of A-dmDT390-bisFv(UCHT1) outlasted even the relapse that occurred after administration of CHOP chemotherapy. This “up-and-down” disease course is typical of what is seen when cancers are treated with immunomodulators, and indicates that the anti-CD3 immunotoxin A-dmDT390-bisFv(UCHT1) functioned as an immunomodulator in this patient.

Patient #7 is a 43-year-old Afro-American male who was diagnosed with mycosis fungoides (CTCL). He received narrow range UVB and clobetasol and his disease was staged as IIB. He had plaques, patches and tumors and an mSWAT of 14. He received 5.0 μg/kg/dose twice a day for 4 days of A-dmDT390-bisFv(UCHT1) and had a PR lasting 14 months, with mSWAT dropping to 1.5. At 15 months he developed two new tumors in his flank. He was placed on Bexarotene and then received local radiation to these tumors. Two years later this patient reports that his most recent tumors regressed and that he has no skin lesions.

Comment: This patient is likely to be in complete remission at present. After a marked improvement he suffered a relapse that responded to local radiation. What is unusual is that be has remained free of skin lesions and tumors for the last two years off all therapy. This indicates that the anti-CD3 immunotoxin A-dmDT390-bisFv(UCHT1) also functioned as a long lasting immunomodulator in this patient. Further, the immunomodulation activity may have been augmented by tumor antigen priming accomplished by local radiation of the flank tumors. The radiation treatment served to i) keep new tumor growth in check, and ii) release antigen into the bloodstream to prime or “boost” the immune response.

Example 3. Use of A-dmDT390-bisFv (UCHT1) as an Immunomodulator

Based on the results obtained in Examples 1 and 2, A-dmDT390-bisFv (UCHT1) is administered as an immunomodulator of late stage metastatic melanoma or renal cell cancer in combination with palliative radiation to induce the priming of activated T cells by releasing tumor antigens. The safety of combining the immunotixin with palliative radiation therapy in patients with stage IV melanoma or renal cell cancer is determined. The tumor response and duration of response at non-irradiated sites (abscopal effect) is documented. T cell activation occurring after administration of A-dmDT390-bisFv(UCHT1) and local radiation to a metastatic lesion of melanoma or renal cell cancer is assessed by following CD4⁺ T cells for HLA-DR and ICOS^(high) T cells using flow cytometry.

20 μg/kg dose (see Example 1) is chosen for immunomodulation. The A-dmDT390-bisFv (UCHT1) dose of 20 μg/kg total is given as 2.5 μg/kg/injection twice a day at 4-6 hours intervals for four consecutive days (days 1-4) into a free flowing IV over a period of approximately 15 minutes. This is ⅓ the MTD found in the phase I portion of the clinical trial treating T cell lymphomas (see Example 1) and 1/10 the MTD found in preclinical studies with mice, rats and squirrel monkeys. The doses on day 2, 3, and 4 are given only in the absence of grade 3 non-hematologic toxicity.

Patients are admitted to the hospital on day 0 for the first two infusions on day 1. Infusions for days 2, 3 and 4 and fractionated radiation are done in the clinic on an outpatient basis. Prior to each of the eight infusions of drug, the patients receive premedication with diphenhydramine (50 mg PO), ranitidine (150 mg PO) and acetaminophen (650 mg). If indicated, an optional premedication of intravenous (IV) corticosteroids (e.g. 50-100 mg hydrocortisone) or oral prednisone is given. The patients also receive 1 liter 5% dextrose/0.45% NaCl IV daily for four days treatment. Prophylactic antibiotics are given for two weeks: acyclovir (400 mg PO) twice a day; Bactrim DS (SMZ-TMP DS 800-160 mg, 1 tablet PO three times a week e.g. Monday, Wednesday and Friday). Patients are also monitored with cytomegalovirus (CMV) and Epstein Barr virus (EBV) PCR tests. EBV PCR is performed at screening, day 5, day 10, and day 23. CMV PCR is performed at screening, day 10, day 23, and day 37. Dose Limiting Toxicity (DLT) is defined as a drug-related non-hematologic toxicity of grade 3 severity or greater except for transient (7 days) grade 4 asymptomatic elevations of transaminases or creatine phosphokinase (CNC) and transient (28 days) grade 3 and 4 lymphopenias. Lymphopenia is not considered a DLT since it is the pharmacologic property of the study drug. Grade 3 reactivation of EBV and CMV are not considered DLTs since they are often associated with lymphopenia. EBV and CMV reactivations higher than grade 3 are considered DLTs. Patients receive fractionated palliative radiation on days 1, 3 and 5 (in between the two infusions on days 1 and 3). The radiation dose is determined by the radiologist on a per patient basis depending on the size and position of the metastatic lesion receiving RT. Vital signs including blood pressure, pulse, temperature, respirations are monitored and patients are retained in or eliminated from the study according to established criteria for safety.

Treatment of the patients with A-dmDT390-bisFv (UCHT1) results in T cell transient depletion followed by T-cell repopulation and activation, and in the breaking of tumor tolerance. The outcome is partial and/or full remission. In some cases, punctuated remission is observed, with periods of partial remission interspersed with periods of recurrence and periods of full remission, even in the absence of administration of additional cytotoxic agents. In some cases, recurrent tumors are treated with radiation to release tumor antigenic to farther prime or sensitize the immune system to the tumor antigens. The protective effects of A-dmDT390-bisFv (UCHT1) are long-lasting, enduring for months and even several years after initial administration.

While the invention has been described in terms of its preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims. Accordingly, the present invention should not be limited to the embodiments as described above, but should further include all modifications and equivalents thereof within the spirit and scope of the description provided herein. 

We claim:
 1. A method of providing immunomodulation to a patient suffering from a cancer which does not bear, or does not uniformly bear, surface CD3 epitopes, comprising administering to the patient an anti-CD3 specific immunotoxin in an amount sufficient to deplete extant T-cells of said patient; and allowing repopulation and maturation of new T cells in said patient in the presence of said non-CD3 cancer cell antigens.
 2. The method of claim 1, wherein said non-CD3 cancer cell antigens are released into circulation as a result of administering an antigen releasing anti-cancer therapy.
 3. The method of claim 2, wherein said antigen releasing anti-cancer therapy is radiation therapy.
 4. The method of claim 1, wherein said step of administering does not break immune tolerance to self antigens in said patient.
 5. The method of claim 1 further comprising a step of providing said non-CD3 cancer cell antigens to said patient to boost an immune response of said patient to said non-CD3 cancer cell antigens, at a period of time after said step of allowing.
 6. The method of claim 5, wherein said step of providing is performed after a recurrence of said cancer.
 7. The method of claim 1, wherein said anti-CD3 specific immunotoxin is A-dmDT390-bisFv (UCHT1).
 8. A method of lengthening survival time of a patient suffering from a cancer which does not bear, or does not uniformly bear, surface CD3 epitopes, comprising administering to the patient an anti-CD3 specific immunotoxin in an amount sufficient to deplete extant T-cells of said patient; and allowing repopulation and maturation of new T cells in said patient in the presence of said non-CD3 cancer cell antigens.
 9. A method of preparing the immune system of a patient to recognize and kill metastatic and/or recurrent cancer, wherein said patient is suffering from a cancer which does not bear, or does not uniformly bear, surface CD3 epitopes, comprising administering to the patient an anti-CD3 specific immunotoxin in an amount sufficient to deplete extant T-cells of said patient; and allowing repopulation and maturation of new T cells in said patient in the presence of said non-CD3 cancer cell antigens. 